Dew Pt Tester June2010

7/31/2019 Dew Pt Tester June2010

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Dew Point TesterThe CVS Dew Point Tester is a chilled mirrorapparatus, which operates by attaining theconditions necessary by the definition of dewpoint.

When a gas is cooled out of contact with liquidwater, the content remains constant but thepercentage saturation increases until it reaches100 percent and moisture begins to condense.The temperature at this point is known as thedew point.

The CVS Dew Point Tester consists of a high-

pressure chamber through which the gas sampleflows. A polished mirror is at one end of thechamber and a viewing window at the other. Theoperator throttles an expandable gas through avalve cooling the polished mirror until the dewpoint is observed. A mercury glass thermometer(Optional Alcohol Filled Thermometers availableupon request) is inserted inside the mirror tubewith the bulb of the thermometer placed close tothe mirror. This allows for greater accuracies intemperature measurement. The temperatureand pressure are then recorded and plotted toobtain the water content of the sample.Conversion of dew points to water content canalso be obtained by use of various publishedcurves.

The Regular Chiller Model A-2 uses propane orcarbon dioxide as a refrigerant. Its constructionoffers greater control and accuratemeasurements.

The CVS Dew Point Tester is a rugged, reliable,mobile instrument that requires no calibration,and is primarily used to measure the moisture

content in any gas. Conforms to ASTM D 1142

and GPA 2140 standards. With ordinary care and

regular scheduled maintenance, the CVS DewPoint Tester will provide continuous service for

many years.

Instruction Manual

Thermometers (Special Orders upon request)

Mercury Filled Alcohol Filled

Part No.Temp.Rating

Part No.Temp.Rating

13-25 -30 to 110F 13-25 RS -30 to 110F

13-38 -100 to 10C 13-27 RS -90 to -40F

13-60 -35 to 50C 13-60 RS -35 to 50C

CVS Regular Chiller Model A-2

c/w Carrying case, 2 thermometers*, Tubing, Fittings,3000 p.s.i Gauge,*Thermometers supplied unless otherwise specified

are:13-25: -30 to 1000F

13-60: -35 to 500C

CVS Regular Chiller Model A-2

Head Office3900 101 StreetEdmonton, Alberta, CanadaT6E 0A5Office: (780) 437-3055Fax: (780) 436-5461

Website: www.cvs-controls.com E-Mail: [email protected] in Canada

Calgary Sales Office205, 2323 32 Avenue NE

Calgary, Alberta, CanadaT2E 6Z3

Office: (403) 250-1416Fax: (403) 291-9487


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Principle

The Bureau of mines Type Dew Point Testeroperates by duplicating the conditions required bythe definition of dew point. Namely, that when agas water vapor mixture is cooled out of contactwith liquid water the absolute humidity, or watercontent, remains constant but the percentagesaturation increases until it reaches 100 percentand moisture begins to condense. Thetemperature at this point is known as the dew point.

Description of Apparatus

The instrument has a pressure tight chamber tocontain the gas or vapor sample and inlet andoutlet valves controlling flow. At one end, a circularclear plastic window allows observation of theinterior and of the mirror on which condensation ofwater occurs. The mirror is highly polishedstainless steel and is attached at its center to a

copper thermometer well. A chiller attached to thethermometer well controls expansion of refrigerantand temperature of the mirror. A thermometerwhose bulb is located close to the back mirrorsurface indicates the mirror temperature. Apressure gauge is attached to the upper side of thechamber and a tripod socket to the bottom.

In certain instances, gas being measured for dewpoint with the dew point tester, Bureau of MinesType, has been through Glycol dehydrators, andconsequently contains glycol vapors as well aswater vapors. This sometimes leads to difficulty in

determining the water dew point because the glycolvapors also condense on the mirror makingobservation of the water dew point difficult oruncertain. The Glycol Filter, Part 13-54 may beused with the dew point tester under suchcircumstances to remove the glycol vapors andincrease the ease of determining the true waterdew point. The filtering material in the glycol filterassembly absorbs both water vapor and glycolvapor, however in use it becomes quickly saturatedwith water vapor while continuing to absorb glycolvapor for a somewhat longer time.

It is during this latter period that water dew points

may be determined satisfactorily, since aftersaturation no more water vapor is removed fromthe gas, and dew points will be as if read withoutthe filter.

Installation

An adjustable tripod is available for mounting the dewpoint tester when used in the field. metal tubingand fittings are provided for making the connection tothe gas pipeline or tank from which the sample is tobe obtained. Hose should not be used for the sampleline because it may add or remove water from thegas, causing possible errors in the dew point. Hosemay be used for the refrigerant connection.

When putting up the apparatus and making tests inthe field, it is necessary that these precautions beobserved.

1. A representative sample must be taken

2. The temperature of the sampling line andDew Point Tester must be above thetemperature of the gas in the pipeline.

3. The sampling line must not contain anycondensed water.

4. There must not be any appreciable reductionin pressure between the gas source and theDew Point apparatus.

5. Dew Point tester should be located as closeas possible to sample point.

After the Dew Point Tester is set up with the sampleconnection to gas supply properly made; connect therefrigerant valve to the tank of propane or otherliquefied gas to be used as a refrigerant. Open thevalve on the tank so that the liquid refrigerant isavailable at the chiller.

Propane is a satisfactory refrigerant for dew pointtemperatures down to about minus 20F. Liquidcarbon dioxide may be used for temperatures tominus 80F or minus 90F.

Test Procedure

1. Purge instrument by flowing the test gasthrough the sample for sufficient time toexpel all air.

2. Open instrument inlet valve completely andreduce the flow of sample by closing theinstrument outlet valve to ensure full samplepressure in the sample chamber

3. Open refrigerant valve periodically for acouple of seconds at a time allowingsufficient time between openings so that themirror temperature is reduced at a rate of notmore than one or two degrees per minute.


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Test Procedure Continued,

4. Simultaneously observe mirror andthermometer, noting temperature at which aspot of moisture first appears in the center ofstainless steel mirror.

5. Allow mirror to warm up, noting temperature

at which moisture spot disappears.

6. Repeat 4 and 5 temperatures observed arewithin 2F for appearance anddisappearance of moisture spot.

7. Record the mean temperature observed asthe Dew Point.

Interpretation of Results

Dew points may be converted to water content byuse of various published curves. The Deaton andFrost Curve is attached as part of these instructions.

Commercial propane is usually considered dry if thedew point is minus 15F or below.

Precautions

Maximum working pressure of modelNo. 35200 Model A-2 is 3000 psi at normaltemperature. This pressure should not be exceeded.

Both window and mirror may be easily removed forcleaning but care should be taken to avoid scratches.

Viewing the dew point mirror through the observationmirror is not only convenient but is a safetyprecaution in case of window failure.

Sometimes it may be necessary to run a test whenatmospheric temperature is below the dew point ofthe gas in the pipeline. It will then be necessary toapply external heat to the sample line to avoidcondensation between the pipeline and dew pointapparatus. The heat should be applied as close toline as possible.In testing some gasses, it may be found that thenatural gasoline dew point of the gas will be the

same, or a higher temperature than the water dewpoint of the gas. It is necessary to visuallydifferentiate between the two dew points. Thegasoline wets the mirror and the film expands in aniridescent ring to cover the entire mirror surface,while the water condensate remains concentrated atthe center.

Use of the Glycol Filter

The filter pressure chamber is installed on the inletof the dew point tester. The pressure chamber hasan easily removable end closure through which isinserted a copper tube containing the filter material.Internal dimensions are such that the sample gas,

when introduced at the side of the pressurechamber is forced to flow through the filteringmaterial before entering the dew point tester. Atnormal rates of flow, no pressure drop is introducedby the filter.

As shown by the drawings, the installation of theglycol filter is made by removing the dew pointtester inlet valve, screwing the filter into theopening from which the valve was removed, andrelocating the inlet valve at the other side of thefilter. In this position, the filter will not interfere withthe dew point tester fitting on the tripod or in thecarrying case. The copper tubing containing thefiltering material is then inserted into the filterchamber and the end closed by the cap. An O-ring sealing gasket is used and, consequently, thecap need only be screwed up hand tight.

Operation of the dew point tester with the filterattached will be normal, except that a brief periodof time should be allowed for the filtering material toattain equilibrium with the sample of gas. Thelength of this period will be determined by thequantity of water and glycol vapor in the samplegas, and may be found running dew points. Twoconsecutive dew points which check and which

have no glycol vapor masking the mirror indicatesatisfactory operation.

The filtering material in the copper tube willeventually become saturated with glycol vapor andwill no longer remove the vapor from the gas, afterwhich it must be discarded and replaced with thenew filter material. Again, the length of time thatone charge of filter material will performsatisfactorily depends upon the glycol vaporcontent of the sample gas. It is important to keepthe charge of the filtering, material small rather thanto increase it in attempting to give it longer life as a

larger volume of filter material will requireproportionately longer times to come to equilibriumand give true dew points.


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Consumables in Natural Gas

The bureau of mines dew point tester is useful fordetermining water content or hydrocarbon dew point innatural and processed gas. Two major advantages are:

1. It can be operated at actual line pressure up to3000 PSI without any mathematical corrections.

2. It is a primary instrument and does not rely onelectronic circuits or mechanical cells, whichneed to be recalibrated or decontaminated.

3. The bureau of mines dew point testeruses the human eye to distinguishbetween the many possiblecondensables in field conditions. Theactual photos below represent a few ofthese conditions and may be used as a

guide to recognize the differences inappearance as the gas falls out on achilled mirror using a CVS Controls dewpoint tester.

Moisture Dew Point

Clean MirrorAppears dark, smooth, andshiny

Moisture Dew PointDew forms a distinct opaque, greyspot approximately -inchdiameter directly in the center of

mirror. Note the clean sharp edgesat this point.

ICE PointCrystals form an irregularpattern. They appear whiteagainst the gray dew pointwhich has enlarged across theentire mirror.

Advanced ICE PointCrystals have joined togetherforming a very irregular pattern.

Hydrocarbon Dew Point

IridescentColorful ring starts in center andexpands quickly over entire mirror.

Hydrocarbon Dew PointAs hydrocarbons condense,droplets begin to form.

Hydrocarbon IIAs temperature continues to fall,droplets join together and runacross mirror.

Advanced HydrocarbonDroplets collect into large dropswhich run down mirror. Eventuallythey freeze and turn white.

(Using Gasoline)


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Hydrocarbon Dew Point

(Using Propane)

Hydrocarbon Dew

PointA fog spreads across entiremirror with dark spot incenter where hydrocarbons

Hydrocarbon IIDark spot enlarges and startsto become irregular shape.

Hydrocarbon IIIAs temperature dropshydrocarbons begin to rundown mirror.

Advanced HydrocarbonWith little surface tension,

sheets of hydrocarbons streamdown mirror and begin topuddle at bottom.

Miscellaneous Dew Points

Alcohol Dew PointA white spot in the center of

the mirror but has distinctedges unlike the sharp edgesof the grey opaque water dewpoint.

Alcohol IISpot becomes larger andincreasingly white with a bluetint around outside

Advanced AlcoholEntire mirror becomes verywhite until droplets form.The drops get larger butcontinue to cling to mirrorwithout freezing.

Glycol Dew PointA light haze covers the entiremirror without beginning inmiddle. It does not changeand will not evaporate.


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3000PSI Dew Point Tester Bureau of Mines TypeModel 35200 A-2


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PART NUMBER DESCRIPTION

13-100A Dew Point Test Tank

13-100B Hose Assembly, c/w Re-Fill Adapter

35214 Tripod

13-1001 Refill Adapter Assembly

13-54* Glycol Filter, *Sold as a Complete Unit

Accessories

ItemPart

NumberDescription Item

PartNumber

Description

1 114V O-Ring, (2 reqd) 12 13-18 Regular Chiller Body

2 13-101 Body 13 13-20 Thermoguard Assembly

3 13-5 Lucite Window 1413-25

Thermometer, -30 to110

0F

13-60Thermometer, -35 to50

0C

4 13-102 Observation Mirror 15 13-23 Adjusting Knob

5 13-6 Window Ret, Nut 16 13-9A Mirror insulating Ring

6 13-7Regular ChillerMirror

17 13-86Carrying Case StandPost

7 56-21Inlet and OutletValve

18 P182-WP Hose Barb

825S14BM-3000

2.5 Safety Gauge,HP

19 13-87* Case Bracket Knob

9 13-78 Mirror Ret. Nut 2035200-CS*

Case Assembly

10 13-9BMirror InsulatingSleeve

11 P182-WPE Hose Elbow * Item Not Shown

Parts List


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Parts List

ItemPart

NumberDescription Item

PartNumber

Description

1 114V O-Ring 13 13-18 Regular Chiller Body

2 124V O-Ring 14 13-20Thermoguard

Assembly

3 13-101LP Body15

13-25Thermometer, -30 to110

0F

4 13-6LP Window Ret, Nut LP 13-60

Thermometer, -35 to

500C

16 13-23 Adjusting Knob

5 13-102 Observation Mirror 17 13-9A Mirror insulating Ring

6 13-79 Lucite Window 18 13-86Carrying Case StandPost

7 13-7Regular ChillerMirror

19 P182-WP Hose Barb

8 56-21Inlet and OutletValve

20 13-87* Case Bracket Knob

9

25S14BM-

1000

2.5 Safety Gauge,

LP 21 35200-CS* Case Assembly

10 13-78 Mirror Ret. Nut

11 P182-WPE Hose Elbow * Item Not Shown

12 13-9BMirror InsulatingSleeve

PART NUMBER DESCRIPTION

13-100A Dew Point Test Tank

13-100B Hose Assembly, c/w Tank Adapter

35215 Tripod

13-1001 Refill Adapter Assembly

13-54* Glycol Filter, *Sold as a Complete Unit

Accessories


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Rev 3, June 2010Printed in Canada

Head Office3900 101 Street

Edmonton, Alberta, Canada T6E 0A5Office: (780) 437-3055Fax: (780) 436-5461

Website: www.cvs-controls.com E-Mail: [email protected]

Calgary Sales Office205, 2323 32 Avenue NE

Calgary, Alberta, Canada T2E 6Z3

Office: (403) 250-1416Fax: (403) 291-9487

CVS Controls Ltd. strives for the highest levels of quality and accuracy. The information included in this publication is presented forinformational purposes only. CVS Controls Ltd. reserves the right to modify or change, and improve design, process, andspecifications without written notice. Under no circumstance is the information contained to be interpreted to be aguarantee/warranty with regard to our products or services, applicability or use.Selection, use and maintenance are the sole responsibility of the end user and purchaser. CVS Controls assumes no liability for theselection use and maintenance of any product.

Documents

Dew Pt Tester June2010